Project 1: PI: D.K.C. Cooper (Abstract) Experimental xenotransplantation (xenoTx), in the form of pig organ transplantation (Tx) in nonhuman primates, has made major advances during the past 10 years since this NIAID funding mechanism was introduced. The problems of early immune rejection and coagulation dysregulation have been greatly reduced, but there is increasing evidence that an inflammatory response may be activating the immune system and/or amplifying coagulation dysfunction. The overall hypothesis that will be investigated in Project 1 is that an inflammatory response plays a significant role in pig kidney and heart graft failure after Tx into baboons, and that its prevention or suppression will result in prolonged graft survival. The mechanisms whereby anti-inflammatory agents prolong graft survival, e.g., by reducing the innate or adaptive immune response, or by minimizing coagulation dysfunction, will be comprehensively investigated. The current proposal will therefore aim to confirm that the combination of (i) unique multi-gene pigs (i.e., pigs with 6 or 7 genetic modifications to protect their tissues from the primate immune response and from the effects of coagulation dysregulation), (ii) an effective immunosuppressive (IS) regimen, and (iii) a targeted anti-inflammatory regimen will, together, allow consistent function of life-supporting pig kidneys and hearts for >6 months in the absence of rejection or coagulopathy. In Aim 1 (investigated in Pittsburgh), we will explore the effect of selected anti-inflammatory agents on life-supporting kidney graft survival in baboons receiving kidneys from multi-gene pigs and using the proven IS regimen (developed during the present 5-year funding period). If the expected outcome is not consistently achieved, we will transplant kidneys from pigs (available to us in 2016-17) expressing different / additional transgenes that might prove advantageous. In Aim 2 (NHLBI), in the heterotopic (non-life-supporting) heart Tx model we shall investigate whether all components of the previously successful IS regimen are essential or whether, after the Tx of a heart from a multi-gene pig (+/- an effective anti-inflammatory regimen), the IS regimen can be minimized, or anticoagulation omitted, thus reducing the risks of long-term therapy, e.g., opportunistic infection or bleeding. Promising approaches will be evaluated in a life-supporting orthotopic model. The proposed studies are innovative in several respects ? (i) unique novel multi-gene pigs, (ii) the subsequent availability of further pigs with possibly advantageous genetic manipulations, (iii) investigation of the role of the inflammatory response in xenoTx. Success in the proposed studies would enable clinical trials of kidney and heart xenoTx as a first step to eliminate current reliance on deceased human organs, making organ Tx available to a greatly expanded number of patients.